Merge commit 'origin'

[lilypond.git] / lily / bezier.cc

diff --git a/lily/bezier.cc b/lily/bezier.cc
index 8f55b3ce507efb8c2595dc8f65bcd0f3e16a0bf2..b341d73754b35ccf5828c9f2372ea65847e5878c 100644 (file)
--- a/lily/bezier.cc
+++ b/lily/bezier.cc
@@ -269,26 +269,23 @@ Bezier::reverse ()
 
 /*
   Subdivide a bezier at T into LEFT_PART and RIGHT_PART
+  using deCasteljau's algorithm.
 */
 void
-Bezier::subdivide (Real t, Bezier &left_part, Bezier &right_part)
+Bezier::subdivide (Real t, Bezier *left_part, Bezier *right_part) const
 {
-  Offset b2[3];
-  Offset b1[2];
-  Offset b0;
-  for (int i = 0; i < 3; i++)
-    b2[i] = control_[i] + t * (control_[i+1] - control_[i]);
-  for (int i = 0; i < 2; i++)
-    b1[i] = b2[i] + t * (b2[i+1] - b2[i]);
-  b0 = b1[0] + t * (b1[1] - b1[0]);
-  left_part.control_[0] = control_[0];
-  left_part.control_[1] = b2[0];
-  left_part.control_[2] = b1[0];
-  left_part.control_[3] = b0;
-  right_part.control_[0] = b0;
-  right_part.control_[1] = b1[1];
-  right_part.control_[2] = b2[2];
-  right_part.control_[3] = control_[3];
+  Offset p[CONTROL_COUNT][CONTROL_COUNT];
+
+  for (int i = 0; i < CONTROL_COUNT ; i++)
+    p[i][CONTROL_COUNT - 1 ] = control_[i];
+  for (int j = CONTROL_COUNT - 2; j >= 0 ; j--)
+  for (int i = 0; i < CONTROL_COUNT -1; i++)
+    p[i][j] = p[i][j+1] + t * (p[i+1][j+1] - p[i][j+1]);
+  for (int i = 0; i < CONTROL_COUNT; i++)
+    {
+      left_part->control_[i]=p[0][CONTROL_COUNT - 1 - i];
+      right_part->control_[i]=p[i][i];
+    }
 }
 
 /*
@@ -296,25 +293,24 @@ Bezier::subdivide (Real t, Bezier &left_part, Bezier &right_part)
 */
 
 Bezier
-Bezier::extract (Real t_min, Real t_max)
+Bezier::extract (Real t_min, Real t_max) const
 {
+  if ((t_min < 0) || (t_max) > 1)
+    programming_error
+      ("bezier extract arguments outside of limits: curve may have bad shape");
+  if (t_min >= t_max)
+    programming_error 
+      ("lower bezier extract value not less than upper value: curve may have bad shape");
   Bezier bez1, bez2, bez3, bez4;
   if (t_min == 0.0)
-    {
-      for (int i = 0; i < CONTROL_COUNT; i++)
-        bez2.control_[i] = control_[i];
-    }
+    bez2 = *this;
   else
-    {
-      subdivide (t_min, bez1, bez2);
-    }
+      subdivide (t_min, &bez1, &bez2);
   if (t_max == 1.0)
-    {
       return bez2;
-    }
   else
    {
-     bez2.subdivide ((t_max-t_min)/(1-t_min), bez3, bez4);
+     bez2.subdivide ((t_max-t_min)/(1-t_min), &bez3, &bez4);
      return bez3;
   }
 }